CHOCOLATE CREAM
4 ounces mascarpone cheese
½ cup (58g) confectioner's sugar, plus more for dusting
2½ tablespoons (13g) natural unsweetened cocoa powder
¼ teaspoon pure vanilla extract
1 cup heavy cream, chilled

DONUT
2½ cups (350g) all-purpose gluten-free flour (I use Better Batter), plus more by the tablespoon (9g)
1½ teaspoons xanthan gum (omit if using Better Batter)
½ teaspoon kosher salt
¼ teaspoon cream of tartar
¼ teaspoon baking soda
¼ cup (50g) sugar
2½ teaspoons instant (breadmaker or rapid rise) yeast
½ teaspoon fresh finely-ground nutmeg (optional)
1 teaspoon apple cider vinegar
1 extra-large egg plus 1 extra-large egg white
9 ounces milk (low-fat is fine, nonfat is not; nondairy is fine)
4 tablespoons (56g) unsalted butter
Oil for frying
1 cup (120g) confectioner's sugar
2 tablespoons (42g) Lyle's Golden Syrup (or honey)
2 to 4 tablespoons water

4 ounces mascarpone cheese 2 ½ tablespoons (13g) natural unsweetened cocoa powder 1 cup heavy cream, chilled 2 ½ cups (350g) all-purpose gluten-free flour (I use Better Batter), plus more by the tablespoon (9g) 1 ½ teaspoons xanthan gum (omit if using Better Batter) 2 ½ teaspoons instant (breadmaker or rapid rise) yeast 1 teaspoon apple cider vinegar 1 extra-large egg plus 1 extra-large egg white 9 ounces milk (low-fat is fine, nonfat is not; nondairy is fine) 4 tablespoons (56g) unsalted butter 1 cup (120g) confectioner's sugar 2 tablespoons (42g) Lyle's Golden Syrup (or honey) 2 to 4 tablespoons water

In the bowl of your stand mixer, place 2½ cups flour, the xanthan gum, salt, cream of tartar, baking soda and sugar. Whisk to combine well. Add the yeast and optional nutmeg, and whisk again to combine well. Fit the mixer with the paddle attachment. Add the vinegar and the eggs, and mix to combine.
In a small saucepan over a medium-low flame, heat the milk and butter, stirring frequently, until the butter is melted and the milk begins to simmer. Remove the pan from the heat and allow the mixture to cool a bit until it reaches about 110 degrees F.
With the mixer on low, add the melted butter and milk in a slow, steady stream until the liquid is absorbed by the dry ingredients. The dough will be very wet. With the mixture on the lowest speed, add 1 to 2 more tablespoons of flour, 1 at a time, mixing well in between additions until the dough comes together more. It should still be wet and sticky if you touch it with your hands, but it should be easy to scrape it off the sides of the mixing bowl with a spatula (see photo). You may not need both tablespoons of flour.Turn the dough out onto a lightly floured sheet of parchment paper, and sprinkle the top lightly with more flour. Divide the dough into 10 to 12 equal parts (each about 95g). Sprinkle each piece of dough lightly with more flour, and, between well-floured hands, roll the first piece of dough into a ball, flatten gently into a disk and place on the prepared baking sheet . Repeat with the remaining pieces of flour, placing the dough about 2 inches apart on the baking sheet.
Spray the doughnuts lightly with water, cover with plastic wrap and place in a warm, draft-free location to rise until about 150% their original size.
While the doughnuts are rising, make the chocolate cream filling. In the bowl of a stand mixer fitted with the paddle attachment, place the mascarpone cheese and mix on high until light and fluffy. Add the ½ cup confectioner's sugar, cocoa powder and vanilla, and mix (slowly at first, so the powder doesn't fly everywhere, later on high) until well-combined. Switch out the paddle attachment in favor of the wire whisk. Add the chilled cream, and whisk on high speed until the cream has thickened and holds relatively stiff peaks. Set the filling aside.
In a large, heavy-bottom stock pot, heat at least 2 inches of oil to about 300 degrees F. Once the oil reaches temperature, fry a few old chunks of bread in the oil. They will blacken pretty quickly. Discard them. Fry another chunk of bread. It should brown more slowly. Fry doughnuts in small batches, about 1 minute (or less) per side, until golden brown all over. Remove with a slotted spoon and drain on a wire rack lined with paper towels. Allow the doughnuts to cool completely before filling, or the filling will melt.
Once the doughnuts are cool, place the chocolate cream in a pastry bag fitted with a large star tip. Plunge the tip about halfway into the side of a cooled doughnut, and squeeze the bag firmly to fill. As the doughnut begins to expand, begin to remove the tip. Repeat with the remaining doughnuts. Sprinkle cooled and filled doughnuts with extra confectioner's sugar.
Fried doughnuts are best enjoyed the day they are made.